In order to obviate such difficulty it has been proposed to provide covered electrodes with arc-stabilizing additives in the coating. These additives maintain during the currentless intervals an ionized atmosphere between the electrode and the work which facilitates the reignition of the arc and stabilizes the welding operation. Wire electrodes used in gas-shielded arc welding are normally not provided with such additives. Therefore other measures have to be adopted to ensure a troublefree welding.
It has been proposed to decrease the pulsation of the output d.c. voltage by providing a smoothing circuit. For example such a circuit for a single-phase power source is described in the British Pat. No. 1,284,636. The smoothing circuit is provided with an inductor, a capacitor and a diode, and connected across the output of the rectifier. The inductor and the capacitor are arranged to store electric energy when the output d.c. voltage of the welding rectifier is high and to discharge this energy into the arc when the output voltage is too low to maintain the arc.